Electric circuit breaker



Nov. 9, 1954 R. c. INGWERsi-:N 2,694,122

ELECTRIC CIRCUIT BREAKER Filed April 22, 1953 2 sheets-sheet 1 f Jr WMM#War/VEZ NOV 9, l954 R. c. INGWERsEN 2,694,122

ELECTRIC cxRcurT BREAKER Filed April 22, 1953 United States Patent CELECTRIC CIRCUIT BREAKER Richard C. Ingwersen, Jackson, Mich., assignorto MechanicalProducts, inc., Jackson, Mich., a corporation of MichiganApplication April 22, 1953, Serial N o. 358,455

7 Claims. (Cl. 20G-116) This invention relates to electric circuitbreakers havingcurrent overload protection and in which such pro--tection is provided by the action of a bi-metallic thermal latchelement arranged so as automatically to disengage van abutment upon theoccurrence of an overload current 2,485,736 issued October 29, 1949, No.2,514,545, prior U. S. Patents No. 2,639,349 issued May 19, 1953, No.2,642,510, issued June 6, 1953, No. 2,665,347, issued January 5, 1954,and application Ser. No. 331,769 tiled January 19, 1953.

ln connection with these electric circuit breakers it is'necessary, inpractice, to provide some means by which theposition of engagement ofthe thermal latch element with its abutment can be finely adjusted afterthe circuit breaker has been assembled and subjected to test. It mayhappen, for instance, that the thermal latch element leavesits abutmenttoo soon, or too late, thereby giving a premature or delayed automaticcircuit breaking action.

In the aforesaid U. S. Patent No. 2,639,349, this adjustment waseffected by means -of a screw connected to engage the thermal latchelement so as to adjust the latch with respect to its position ofengagement with the abutment. This mode of adjustment, while effective,necessitates positive and mechanical flexing of the thermal latchelement, whereby attention must be given to constructing the latchelement so that it is capable of taking care of such flexing movementwithout having any deleterious effect upon the ability of the latchelement to deect, under the heat of the conveyed electric current, anddisengage the abutmentupon the occurrence of the predetermined currentoverload. The construction of the thermal latch element itself permitsthe latch to be kept to finely calibrated limits to provide the desiredautomatic and instant circuit breaking operation and it becomesdesirable, therefore, that the latch element should not be subjected topositive mechanical deflection in order to adjust its position ofContact with the abutment surface, as disclosed in the said U. S. PatentNo. 2,639,349.

lt is an important object of the present invention to provide animproved thermal latch and abutment assembly in which adjustment of theposition of contact of the thermal latch element with its abutment isreadily possible without the necessity of subjecting the thermal elementitself to mechanical flexure.

Another object of the invention is to provide an improved thermal latchand abutment assembly in which the abutment is capable of being readilyadjusted to adjust thc position of contact of the thermal element withrespect to the abutment.

The above, and further objects and advantages of the invention, residingin the construction, arrangement and combination of parts, will appearclear from consideration of the following detail description withreference to the accompanying drawings and the appended claims.

ln the drawings:

Fig. 1 is a vertical sectional view of an electric circuit breakerembodying the present invention, with the thermal latch shown engagedwith its abutment,

Fig. 2 is a section on the line 2-2 of Fig. 1,

Fig. 3 is an enlarged elevational view of the thermal lFa'tchZandabutment assembly looking upon the front of 2,694,122 Patented Nov. 9,1954 ice gig. 4 is a vertical'section on the line 4-4 of Fig. 3, an

Figs. 5 and 6 are diagrammatic views of alternative adjustable abutmentsand latch assemblies.

Referring to the drawings,in Figs. 1 to 4 there is disclosed anelectrical circuit breaker constructed and arranged to operatesubstantially as disclosed in the above mentioned patents and co-pendingapplications, but in which the thermal latch element '10 is arranged toengage an abutment surface 12 defined at the lower end of a plate member14 secured upon the actuator plunger 16 (constituting support structurefor the abutment) at its opposite end, as by the cross rivet 18.

ln the particular example-illustrated in these 'figures there is onlyone thermal latch element arranged to engage on one side of the actuatorplunger, this latch element being connected with a guide plate 20slidably and guidedly engaged with respect to the opposite side of theactuator plunger. It is to be understood, however, that the constructionmay be modified to provide a thermal latch element and abutment uponopposite sides of the actuator plunger, with the adjustable abutmentconstruction being, for instance, as disclosed in Fig. 6, to bedescribed later.

The actuator plunger 16 is formed with opposite ledge surfaces 22, 22with which the outwardly directed abutment surface 12, and a similarsurface 24 on a wear plate 26, engage, the plate 26 providing a wearsurface, at 24, for the slidable engagement of the guide plate 20.

For adjusting the point of engagement of the edge 10 of the thermallatch element with the abutment surface 12, theplate 14, which isdeflectable in its lower portion, containing the abutment surface, isformed with an inturned tongue 14', the free end edge of which isengaged by the conical end v28 of an adjustment screw 23. This screw isshown as extending vertically through a screw-threaded bore 30 in thelower end portion 16 of the vplunger 16. The screw-has its screw-driverslot 28" exposed to an enlarged vertical cavity 16" in the piunger, inwhich cavity the coil spring 32 for restoring the plunger to itsreleased re-set position is housed.

The tongue 14' may be pressed out of the material of the plate 14, withthe formation of a rectangular slot 14 (Fig. 3) in the plate.

When assembled within the casing, as seen in Figs. 1 and 2, the spring32 extends between the screw-driver end of the adjustment -screw 28 anda nut 34 mounted within an opening 36 in the bottom of the casing. Thisopening is finally closed by a screw plug 38, screwed through the nut34, but, with the screw-plug removed, it is possible'to adjust the screw28 by inserting a screwdriver through the center of the spring 32 toengage the screw-driver slot 28".

Rotation of the screw 28 in one direction or the other, by contact ofthe screw end 23 with the tongue 14', will cause the abutmentvsurface'12 to move outwards or 'inwards wthrespect to its ledge andguide surface 22 and thereby adjust the position at which the latch edge10' engagesvthe Vabutment surface. By this adjustment of the abutmentsurface, therefore, the latch edge 10 can be made to engage the abutmentsurface either farther inwards or outwards, depending upon the amount ofthermal distortion needed for the latch edge to disengage the abutmentsurface upon the oc currence of the predetermined current overload atwhich the circuit breaker is required to operate to automaticallyinterrupt the circuit closed at the movable contacts 40, 40 and theiixed contact 42, 42.

ln Fig. 5, there is illustrated an alternative form of adjustableabutment and thermal latch assembly. In this form of the invention, theabutment is in the form of a block 44 mounted for lateral sliding andtranslational movement with respect to a rectilinear recess 46 formed inthe abutment support structure 48, which structure may form part of are-set actuator plunger, as disclosed in Figs. 1 4. The thermal latchelement is indicated at 50 with its free distortable edge 50 inengagement with the abutment surface 44' provided by the abutment block44. The abutment block has a cenv tral lateral screw-threaded bore 52 inwhich the screwthreaded end 54' of an adjustment screw 54 engages,

this screw having its screw-driver slot 54 exposed to the side of thesupport structure (or actuator plunger) remote from the abutment block44 and being constrained against axial motion, when rotated, by thekeeper plate structure 56. With this construction and arrangement,rotation of the screw 54 in one direction, or in the opposite direction,will cause the abutment block 44 to be either drawn into, or projectedout, with respect to the recess 46 and thereby cause the latch edge 50'to be set at the desired position along the abutment surface 44.

In Fig. 5, as in Figs. 1 to 4, the adjustment abutment is disclosed asapplied to a one-side latch assembly.

An alternative adaptation of the invention for a twoside latch assemblyis disclosed in Fig. 6. In this form of the invention the supportstructure 58, which may constitute a re-set actuator plunger, hasrecesses 60, 60, formed in its opposite sides, and similar abutmentblocks 62, 62 are slidably mounted in each said recess, these blockspresenting abutment surfaces 62', 62' to the thermally distortable freeend edges 64', 64 of a pair of bi-metallic thermal latch plates 64, 64.The blocks 62 have axially aligned screw-threaded bores 62, 62" whichare of opposite direction (i. e. right and lefthand threads) and receivethe corresponding screwthreaded portions 66', 66 of an adjustment screw66. This screw inter-connects the two abutment blocks through the mediumof a keeper plate structure 63 which constrains the screw against axialmovement, when rotated, so that its rotary motion, in either direction,produces lateral displacement of the abutment blocks 62, 62 with respectto their recesses 60, 60. One end of the screw 66 exposes a screw-driverslot 66" by which the screw can be adjusted, as desired. It will be selfunderstood, with such a construction and arrangement of parts asillustrated in Fig. 6, that rotation of the screw 66 in either directionwill produce simultaneous displacement of the abutment blocks towards oraway from each other, whereby the ends 64', 64 of the thermal latchplates can be adjustably and similarly set with respect to theirabutment surfaces 62', 62.

Having thus disclosed my invention, what I claim as novel and wish tosecure by Letters Patent is as follows:

l. In an electric circuit breaker having current overload protection andincluding fixed and movable contact means, a bi-metallic latch inelectrical connection with said movable contact means, and an abutmentwith which an edge of said latch engages to hold the contacts closed,support structure for said abutment, means mounting said abutment uponsaid support structure for translational movement with respect to saidlatch edge, adjustable means connected with said abutment for impartingsaid translational movement to the abutment to adjust the position ofcontact of the latch edge with said abutment, and spring means connectedwith said latch for holding said edge firmly engaged against saidabutment.

2. An electric circuit breaker as claimed in claim l, said abutmentincluding a plate member defining an abutment surface at one end, meansmounting one end of said plate member upon said support structure, saidend with the abutment surface being deflectable, an adjustment screw onsaid support structure, and means on said plate member in engagementwith said adjustment screw for deecting said plate end, by adjustment ofsaid screw, to vary the position of engagement of the latch edge withsaid abutment surface.

3. An electric circuit breaker as claimed in claim l, said supportstructure including a guide surface and said abutment including a blockslidably supported with respect to said guide surface, an adjustmentscrew on said support structure and engaged with said abutment block,and means constraining said block to partake of sliding movement withrespect to said guide surface upon rotation of said adjustment screw.

4. An electric circuit breaker as claimed in claim 1, said supportstructure defining opposite sides with a guide surface on each side, andsaid abutment including a block slidably supported with respect to eachsaid guide surface, whereby there is an abutment block on opposite sidesof the support structure, an adjustment screw inter-connecting saidabutment blocks, and means constraining said blocks to partake ofsliding movement with respect to said guide surface in oppositedirections, and to a similar extent, upon rotation of said adjustmentscrew.

5. An electric circuit breaker as claimed in claim 4, said adjustmentblocks having axially aligned screwthreaded bores of opposite directionand said adjustment screw having oppositely directed screw-threadedportions engaged in said bores.

6. In a thermal latch and abutment assembly for an electrical circuitbreaker, said assembly including support structure, a thermal latchmovably mounted with respect to said support structure and an abutmenton said support structure for engagement by an end edge of said latch tohold the latch in the latched position, a guide surface on saidstructure, means mounting said abutment on said structure for movementwith respect to said guide surface, and adjustment means on said supportstructure and connected with said abutment to adjust the abutment withrespect to said guide surface, whereby to vary the point of engagementof said latch edge with said abutment, and spring means connected withsaid latch for holding said edge irmly engaged against said abutment 7.In an electric circuit breaker having overload protection, fixed contactmeans, movable contact means in opposed relation to said xed contactmeans, a bimetallic latch in electrical connection with said movablecontact means, guide structure including an abutment surface, meansmounting said movable contact means and said bi-metallic latch formovement as a unit relatively to said guide structure for engaging anedge of said latch with said abutment surface, said latch edge beingdeflectable from engagement with said abutment surface under theinfluence of the heat of the conducted current, means mounting saidabutment for adjustment upon said support structure in the direction ofsaid deflection, and spring means connected with said unit for holdingsaid latch rmly engaged with said abutment, said spring means beingoperative to move said movable contact means sharply away from themovable contact means when said latch disengages said abutment.

References Cited in the file of this patent UNITED STATES PATENTS Number

